Plugin does not work

I installed the plugin and for first few cases, gift card mail did come. But not any more. I tried to edit a template and after that plugin completely stopped working. And when I set order status to completed from processing , plugin thorws a fatal error like the following:

Fatal error: Uncaught Error: Call to a member function is_type() on boolean in /home/ronewyor/testing.domainname.com/foxholt/wp-content/plugins/woo-gift-cards-lite/public/class-woocommerce_gift_cards_lite-public.php:717 Stack trace: #0 /home/ronewyor/testing.domainname.com/foxholt/wp-includes/class-wp-hook.php(289): Woocommerce_Gift_Cards_Lite_Public->mwb_wgm_woocommerce_order_status_changed(28227, ‘processing’, ‘completed’) #1 /home/ronewyor/testing.domainname.com/foxholt/wp-includes/class-wp-hook.php(311): WP_Hook->apply_filters(”, Array) #2 /home/ronewyor/testing.domainname.com/foxholt/wp-includes/plugin.php(478): WP_Hook->do_action(Array) #3 /home/ronewyor/testing.domainname.com/foxholt/wp-content/plugins/woocommerce/includes/class-wc-order.php(373): do_action(‘woocommerce_ord…’, 28227, ‘processing’, ‘completed’, Object(Automattic\WooCommerce\Admin\Overrides\Order)) #4 /home/ronewyor/testing.domainname.com/foxholt/wp-content/plugins/woocommerce/includes/class-wc-order.php(221): WC_Order->status_transition() #5 /home/rone in /home/ronewyor/testing.domainname.com/foxholt/wp-content/plugins/woo-gift-cards-lite/public/class-woocommerce_gift_cards_lite-public.php on line 717

Horrible plugin.